EFTPS: The Easiest Way to Pay Your Federal Taxes - "The Electronic Federal Tax Payment System tax payment service is provided free by the U.S. Department of the Treasury. After you've enrolled and received your credentials, you can pay any tax due to the Internal Revenue Service (IRS) using this system."

Free Tax Filing - If you're one of the more than 56 million American taxpayers with an adjusted gross income of $25,000 or less, you qualify for free online tax preparation and filing through the Quicken Tax Freedom Project.

Tax Statistics: IRS - This IRS site provides a wealth of information about the financial composition of individuals, business taxpayers, tax exempt organizations and more. This data has been sampled from all kinds of returns and sorted in lots of interesting ways.